This application is related to an improvement in the control of an aspirant line (sometimes referred to as the fluid flow system) in a surgical irrigation/aspiration (I/A) machine of the type used for supplying irrigation solution to operative sites (generally the eye) and removing such infusion liquids and macerated tissue therefrom. In such surgical machines it is critical that the pressure at the operative site be maintained at relatively constant limits, particularly where the total volume within the operative site is small in relation to the rest of the fluid in the system. Such surgical devices are generally described in U.S. Pat. Nos. 3,589,363; 3,693,613; and 3,902,495; and in applicant's own pending applications Ser. Nos. 674,064, filed Nov. 14, 1984 and 647,818, filed Sep. 6, 1984.
The previously mentioned patents and applications describe irrigation/aspiration machines which are used in conjunction with a surgical handpiece. The hand instrument of such machines either cuts or ultrasonically breaks apart unwanted tissue and material, while simultaneously introducing an irritant into the eye chamber and withdrawing excess fluid and macerated tissue. Treatment or irrigation fluid is introduced into the operative site at a constant low pressure. This introduction of irrigating fluid is to provide a replacement for the fluids which are withdrawn or lost from the operative site such as the eye chamber. The withdrawal of fluid and suspended materials from the operative site is called aspiration, and under ideal conditions and procedures, there is no change in the fluid or chamber pressure as a result of this irrigation/aspiration procedure. Realistically, however, it is impossible to achieve an ideal constant pressure at the operative site since the aspiration procedure is intended to remove solid materials which sometimes occlude or block the fluid withdrawal openings of the surgical handpiece.
Some of the problems with control of fluid content and pressure within the operative site during the use of irrigation/aspiration procedures is discussed in detail in the aforementioned U.S. Pat. No. 3,693,613, issued Sep. 26, 1972 to Charles Kelman for a surgical handpiece and flow control system for use therewith. As explained in this patent, when the surgical handpiece is inserted into the operative site, it is very important that the pressure within the operative site be maintained within a certain range of values. If the pressure is not maintained at a prescribed level, parts of the operative site, such as the eye, can be damaged.
To aid in controlling this critical pressure, it has become customary to provide a pressure monitoring section in the I/A machine which continuously senses the vacuum in the aspirant line. When the vacuum exceeds a prescribed limit, a vent valve is opened to the atmosphere to reduce the vacuum in the aspirant line. For example, the aspiration sub-system most frequently comprises a peristaltic aspiration pump used to withdraw the aspirant through a tube or line, an intermediate point of which is interconnected to the pressure monitoring section of the I/A machine. The monitoring section responds to pressure changes in the aspirant line by sending some type of signal to the vent valve which responds by opening the aspirant line to the atmosphere. The function of the vent valve is to provide for pressure equalization between atmospheric pressure and the hydraulic pressure in the fluid flow system. This equalization function is commonly referred to as "venting", and negates a vacuum buildup in the aspiration line. The peristaltic pump is operated by the surgeon by use of a foot switch or pedal normally having an "off" position, multiple "on" positions, and a "transition" position. Disposable surgical irrigation/aspiration set-up kits are provided to the surgical team for selectively connecting the irrigation/aspiration machine to: (1) the hand instrument being used by the surgeon, (2) to the sterile fluids being used for irrigation, and (3) through the peristaltic pump to the disposable receptacle which receives these fluids and tissues as they are aspirated from the operative site. A new setup kit is provided with each surgical operation and is disposed of after the surgery is performed. Applicant's previously mentioned pending applications are directed in part to such set-up kits, as is U.S. Pat. No. 4,418,944 to Haines et al, wherein a set-up kit is disclosed which includes a disposable, releasable connector called a "cam lock tee".
The Haines connector is affixed to the aspiration tubing and is snapped into place in a corresponding receptacle on the front of the irrigation/aspiration machine. This connector has an air passageway longitudinally therethrough and a branch thereof which leads from the longitudinal air passageway through an opening on the side of the connector. The opening mates with a corresponding opening in the receptacle on the face of the I/A machine leading to the vent valve and its associated monitoring equipment within the machine. When the connector is properly seated there is direct communication between the aspiration line and the interior of the irrigation/aspiration machine whereby the critical air pressure (vacuum) within the aspiration line may be monitored.
In the Haines et al connector, as in the connector described in applicant's previously filed pending applications, proper seating of the connector in the front panel receptacle is critical. Rather than being simply inserted directly into an opening on the front panel, some type of rotating and locking of the connector has been required. Because of the peculiar shape of the connector and the transverse air passageway, proper seating of the connector and reliable alignment of the branch line and the air passageway into the machine have been difficult at best. Additionally, there are problems in creating a tight seal between the connector and the entrance in the receptacle to the machine air passageway to prevent a loss of vacuum in the aspiration line. It previously has been believed that the peculiar shape and use of a connector or coupling device such as the previously known "cam lock tee" has been necessary to ensure that there is no displacement or rotation of the coupling during a surgical procedure. Any such displacement or rotation not only threatens the seal, but also may detrimentally effect the operation of the pump. It is also important that the aspirant line remain horizontal to the extent possible to promote proper aspirant flow. The loss of vacuum resulting from poor sealing of the connector or improper alignment of the aspirant line leading to the peristaltic pump are the primary problems in the use of existing disposable set-up kits. It was therefore to the improvement of the coupling of the aspirant tubing to the irrigation/aspiration machine, and to the overcoming of all of the above discussed problems, that the present inventor turned during the development of the invention disclosed herein.